Most really good weed sells for $300-400 an ounce around my area, or $100-130 per quarter. Most indoor grows yield 200-500 grams per square meter, but I guess with some strains 600 is possible if you do everything perfectly. If you grow a lot of volume and have to sell by the pound, that price drops A LOT. Around here a pound usually goes for $2000 or so - the same weed would cost $5000 purchased by the ounce. So how much you save depends on how much you would have otherwise spent if you had to buy it.
If you are really trying to figure out how much you could MAKE as a dealer, then that depends on how much space you plan to use and how much money you spend setting up and maintaining your grow. Then you have to figure in how much your fines will be when you get caught and how much your freedom was worth when you eventually lose it.
You are literally 20x more likely to get caught as a dealer than you are as a simple cautious grower who never tells a soul that they grow.